This invention relates in general to housing of agricultural animals, such as dairy cattle, and is more particularly directed to a curtain that can be raised or lowered to control free air flow through an open wall of an agricultural building, such as a free-stall barn. The invention is more particularly concerned with an improved curtain arrangement that ensures proper ventilation in all weather conditions, and by which the amount of ventilation is easily changed by simply raising or lowering an upper portion of the curtain assembly, while avoiding wear of the curtain by undue folding or bending, and also avoiding problems from dirt and vermin collecting in the curtain.
Free-stall dairy barns, also known as loose housing, have become an attractive option for dairy farmers who want to maintain and manage a large dairy herd. The advantages of the free-stall housing system include reduction of bedding per cow, less space per cow, ease of manure removal, reduced udder washing time before milking, higher milk quality, and less frequent udder injury. The large cattle population housed within the barn requires the design of the barn to pay attention to the need for sufficient ventilation. During the warmer months, the sides of the barn can be completely open to air flow, but during the colder months the air flow needs to be limited and controlled. To keep the cows healthy, excess moisture has to be vented off, and the cows have to be kept reasonably dry. Normally, a vent is provided in the barn roof ridge to allow the warm moist air to escape. Side curtains are provided on the walls of the barn and these are opened to allow air flow, and can be partially or completely closed to protect the cows from cold and drafts.
Several ventilation curtains for dairy barns and other agricultural buildings are described in the literature. One example of a ventilation curtain assembly that uses a roller blind construction is described in U.S. Pat. No. 6,273,813. Other curtains and ventilation systems, which can also be adapted for poultry buildings, hog barns, etc., are discussed in U.S. Pat. Nos. 5,556,644 and 6,079,365. Also, as a matter of background, general guidelines for constructing and employing free-stall barns for a dairy herd are found in Robert E. Graves, Guideline for Planning Dairy Free-stall Barns, Northeast Regional Agricultural Engineering Service Cooperative Extension, Ithaca N.Y., 1995. Other useful background information can be found in Moeller et al., Free-Stall Loose Housing for Dairy Cattle, ID-63, Purdue University Cooperative Extension Servic; Hammond, Dairy Free Stall Design, University of Georgia College of Agricultural and Environmental Services Cooperative Extension Service; and Chastain et al., Dairy Lighting System for Free Stall Barns and Milking Centers, Pub. AEU-12, University of Minnesota Extension Service, Department of Biosystems and Agricultural Engineering, August 1966.
There is typically a bird barrier on the indoor side of the curtain, that is, a mesh or screen, to prevent or discourage birds from flying into the barn. In addition, there may be straps or bars on the outdoor side to prevent the curtain from billowing out due to wind. The bird barrier also prevents the curtain from billowing inward due to wind.
Cows typically transpire a large amount of moisture, and this moisture has to be removed from the building to keep the cows healthy. Air is generally exhausted by natural convective air flow through an opening or openings in the roof. During warm weather, there is free flow of air into the building because the curtains are completely opened. However, in cold weather, the curtain limits the air flow into the building, and it is better to allow cold air to enter from above the cows to prevent drafts. The animals can endure the cold air, but cannot be allowed to be wet or subjected to cold moving air. Consequently, the curtains are kept mostly closed, and preferably there is an opening at the top for ventilation. In past curtain systems, the curtains have simply been lowered from the top, and allowed to loosely and randomly fold at the bottom or base, where dirt can accumulate and insects can infest, and where the curtain can become damaged from undue flexing.
Dairy herds have become much larger in recent years, necessitating larger buildings. These larger buildings become more difficult to ventilate. By increasing the side wall height, more air is allowed to enter for better ventilation. However, these higher side walls present a greater challenge to design of flexible curtains.
In the past it has been necessary to use two curtains, one above the other, to cover these higher sidewalls. These systems are more difficult and more costly to install. All the components of each system must be duplicated. Additionally, much air movement is lost because of the side wall area used up by the installation components required in this type of dual-curtain system. For example, a shelf just be provided to support the bottom portion of the upper curtain as the top is lowered for ventilation, and the fabric at the bottom is then randomly folded onto the shelf. Also, some apparatus must be used to hold up the top of the lower curtain. This takes additional space from the sidewall area. Also another shelf is required at the bottom of the side wall to support the bottom of the lower curtain as the top of the lower curtain is let down for ventilation. The total side wall area is significantly reducedxe2x80x94with a consequent reduction in ventilation capacityxe2x80x94when conventional two-curtain systems are used to ventilate large, high-side-wall dairy buildings.
Accordingly, it is an object of this invention to provide a ventilation curtain arrangement for a free-stall dairy barn or other building in which livestock are housed, and which overcomes the drawbacks of the prior art.
It is another object to provide a curtain arrangement that can be easily moved from a closed position, to any of numerous partly opened positions, and to a mild-weather open position.
It is a further object to provide a sliding curtain assembly in which an upper curtain can be raised or lowered to slide past a lower curtain.
It is a still further object to provide a curtain arrangement in which the flexible fabric curtains can be rolled for summer storage.
In accordance with an aspect of the present invention, a sliding curtain arrangement is provided on at least one wall of a free-stall barn for or other agricultural building in which animals are housed. The wall on which the curtain is mounted is open for ventilation, except for a generally wide-mesh bird barrier. The curtain arrangement comprises a lower curtain assembly and a sliding upper curtain assembly. The lower curtain assembly is mounted on the building wall and includes a horizontal upper hem pipe supported at a midway vertical position on the wall, a horizontal lower hem pipe, and a flexible fabric lower curtain supported between the upper and lower hem pipes. The upper curtain assembly is mounted for vertical sliding action on the wall at a vertical position above and overlapping the position of the upper hem pipe of the lower curtain assembly. The upper curtain assembly includes a horizontal upper hem pipe, a horizontal lower hem pipe, and a flexible fabric upper curtain supplied between the associated upper and lower hem pipes. The upper and lower hem pipes of the upper curtain assembly have at least some freedom of travel in the vertical direction. A hoisting mechanism on the building wall is coupled to the upper hem pipe of the upper curtain assembly and is adapted for raising and lowering the upper curtain assembly between a raised severe-weather position (in which ventilation through the wall is closed off) and a lowered mild weather position (in which the upper portion of the wall above the lower curtain assembly is open to permit ventilation).
In one favorable arrangement, there are roll-up mechanisms, which include rotary dollies connected with the lower hem pipes of the upper and lower curtain assemblies, both of which travel on an associated vertical rail (this can simply be a vertical pipe, or may be a track or channel). These rotary dollies are adapted for rotating the lower hem pipe to wind up the respective curtain. The lower rotary dolly can be used to raise the bottom of the lower curtain and thus open a lower position of the wall for ventilation, or to roll up the lower curtain for storage. The rotary dolly of the upper curtain is used for rolling up the upper curtain for summer storage, but does not interfere with the upward and downward sliding action discussed above. The rail is intended to prevent the roll up mechanism from rotating, so that all the rotation goes into winding up the lower hem pipe and curtain.
The hoisting mechanism for raising and lowering the upper curtain can include a main cable, one or more sheaves attached onto an upper transverse beam on the associated wall, and through which the main cable passes, a plurality of secondary cables attached at one end to the main cable and at another end to the upper hem pipe of the upper curtain assembly, and a plurality of sheaves each associated with a respective one of the secondary cables. A windlass, which can be hand-cranked or motor driven, can be used for winding and unwinding the main cable to lift and lower the upper curtain assembly.
Other important features may include input adapters for a rotary drive inputs of the dollies, and these may have a loop adapted to removably receive a shepherd""s crook drive rod so that the curtains can be wound up and unwound using a portable rotary power tool, e.g., a portable drill. Vertical anti-billowing retaining straps situated outside of said upper and lower curtain assemblies restrain the curtain from billowing in the wind. These straps can also be used inside the barn to prevent billowing inward, in construction where bird barriers are not used. Also, vertical end covers are preferably disposed over right and left edges of the upper and lower curtain assemblies, with each end cover being attached by hinges to supports on the wall. This construction permits the covers to swing between a closed position concealing edges of the upper and lower curtain assemblies and an open position that provides access to the edges.
The fabric curtain may be of any of a variety of tough flexible materials, which may be woven and coated with vinyl or polyethylene, and may be opaque or translucent. Because the curtains slide past one another, rather than being rolled or folded to change the ventilation aperture, there is less wear on the curtains, and less chance to collect dirt and vermin than with other systems.